This invention relates to preparation of a comestible beverage from a substance contained in a cartridge and to cartridges containing a substance for preparation of a beverage.
There are several reasons for employing cartridges to contain substances for preparation of aqueous fluid comestibles, particularly beverages, which include considerations of hygiene, optimal storage and keeping qualities of the material employed to produce the fluid comestibles and which include control of the quality and reproducibility of the fluid comestibles prepared. Among available cartridges, including those which have found particular applicability for providing single servings of espresso coffees, cartridges which are sealed and which are opened under the effect of water injected under pressure satisfy the requirements mentioned above. In general, cartridges which contain substances for the preparation of fluid comestibles may be differentiated by their opening systems and ease of use and cost of manufacture.
Great Britain Patent Specification 938,617 discloses a sealed cartridge which has an internally disposed filter positioned to form two compartments in the cartridge. The cartridge is employed for preparation of a beverage by positioning it in an infusion apparatus system which provides for piercing opposing cartridge faces. That system, however, has piercing elements exposed which could be injurious and does not ensure cleanness during extraction or easy release of the cartridge and any material contained therein on completion of extraction.
Swiss Patent 605 293 and its counterpart U.S. Pat. No. 4,136,202, disclose a cartridge which, by design, has a weakened wall formed by marks for forming a line of weakening to effect preferential tearing under the effect of pressure introduced into the cartridge. This feature, however, has a disadvantage of increasing the complexity, and hence the cost, of the cartridge because the materials used have to be fabricated very precisely if opening of the cartridge is to be correct and reproducible. In addition, unless the cartridge contains a completely soluble substance, the cartridge contains a filter which is strong enough to retain a substance, such as coffee grounds, therein during an extraction process, which itself tends to be costly.
As described by Fasano in U.S. Pat. No. 3,607,279, French Patent No. 1,537,031 and French Patent Application Publication No. 2,033,190, a first foil strip of aluminum or plastic or other air-impervious material is formed to provide a plurality of cup body pockets in the strip for containing a material for preparation of a beverage, and a second strip provides a cover for the cup pockets opposite the cup base face. To obtain a beverage, this cartridge is employed with an apparatus embodied to provide elements which pierce both the cover face and cup body base face, to provide for introduction of a liquid and release of a beverage, or which pierce only the cover for introduction of extraction fluid, in which case, liquid introduced into the cartridge is relied upon to assist opening the cup body base face to provide for release of the beverage. The apparatus system however, is difficult to manufacture and the process is difficult to carry out because of the perforated plate and spring arrangement employed for engaging the base face of the cartridge, which makes the process operations delicate and difficult to control.
As described, in particular, in the Fasano U.S. disclosure, the cartridge contains at least one filter therein except when the beverage preparation material is a liquid, and it is disclosed that it is possible to eliminate a sheet of filter material by making the pierced holes so small that they themselves serve as a filter. In the case when only the cover is pierced, it is stated that it is possible to weaken the cup base face at spaced locations or to make an entire region of the cup base face weaker than the cover face to carry out the base opening. It is stated that opening of the base is possible by replacing piercing teeth with configurations which leave marks which first weaken the cup body base material so that the body base is weakened to make it more readily penetrable under the pressure of the liquid than if the cup base face were left intact. Thus, in a first phase, weakened areas are created by mechanical action upon the face, after which, in a second phase, the effect of pressure of water introduced in the cartridge results in rupturing the face at the weakened zones. It also is disclosed that the cup body base may be weakened relative to the cover by using a thinner or otherwise inherently weaker material for the cup body, it being disclosed that the pressure at which the base face will rupture to some extent being varied by changing the thickness or compactness of the filter material above the base face.
As the Fasano disclosure teaches, the liquid introduced to prepare the beverage moves by gravity, and it is believed that, when proceeding in accordance with the process and apparatus system of the Fasano disclosures, the tearing of the face of the cartridge will not necessarily be sufficient to guarantee a regular flow of a liquid therethrough, and that the maximum pressure in the cartridge is reached during opening of the cartridge. The subsequent pressure in the cartridge, therefore, is at most equal to the pressure which effects the opening and that is fairly restrictive in terms of use for, in particular, obtaining single serving amounts from substances which require extraction in a short period of time with small amounts of water. Thus, the substances are not extracted sufficiently to achieve a desirable and/or efficient extraction, particularly in the case of such as preparation of an espresso coffee.
Accordingly, problems addressed by the present invention include how to obtain a high quality uniformly reproducible fluid comestible product from an economical carrying package and how to do so in a system which remains clean and which is easy to maintain, while utilizing the advantages of employing cartridges to contain substances for the preparation of fluid comestibles, including beverages.